Pressure fluid operated pressure intensifier



E. A. ROCKWELL PRESSURE FLUID OPERATED PRESSURE INTENSIFIER Filed June 9, 1944 May 19, 1953 6 Sheets-Sheet l m m m m ATTORNEY May 19, 1953 E. A. ROCKWELL 2,638,747

PRESSURE FLUID OPERATED PRESSURE INTENSIFIER Filed June 9, 1944 e Sheets-Sheet 2 mm m Mm em Rock ATTORNEY y 1953 E. A. ROCKWELL 2,533,747"

PRESSURE FLUID OPERATED PRESSURE INTENSIFIER Filed June 9, 1944 6 Sheets-Sheet d'; n Rockwgll 1 ATTORNEY May 19,1953 E. A. ROCKWELL 2,638,747

PRESSURE FLUID OPERATED PRESSURE INTENSIFIER Filed June 9, 1944 6 Sheets-Sheet 4 I E T I l 3 Jon-. d N F J g g I1 INVENTOR- Edward fl.R0ckweZl ATTORNEY E. A. ROCKWELL PRESSURE FLUID OPERATED PRESSURE INTENSIFIER Filed June 9, 1944 May 19, 1953 6 Sheets-Sheet 5 INVENTOR. Edward/1. fiockwell. BY

ATTORIVE Y y 19, 1953 E. A. ROCKWELL 2,638,747

PRESSURE FLUID OPERATED PRESSURE INTENSIFIER Filed June 9, 1944 6 Sheets-Sheet 6 D wk N f 41-- .'.'.I. INVENTOR.

Edward H. Rockwell ATTORNEY example on automotive vehicles.

Patented May 19, 1953 UNITED STATES PATENT OFFICE PRESSURE FLUID OPERATED PRESSURE INTENSIFIER 9 Claims.

My invention relates particularly to power units in compact form, that may be used to perform work, as for example in the operation of parts of automotive vehicles, such as brakes, etc.

The object of my invention is to provide a power unit which is capable of being used advantageously for the operation of any desired part to be moved and which is especially applicable to the operation of brakes in automotive vehicles, such for instance as automobiles, airplanes, etc. The object of my invention is also to provide a power unit in compact form for the operation of any desired part to be moved, as for Another object is to provide a unit of this character in such a manner as to obtain an effective ratio of input force to output force. A further object is to provide an effective means for obtaining liquid compensation in the parts which operate the power valves. Still a further object is to locate an of the controlling connections for the power unit at one end thereof. it further object is to locate all of the valves of the unit at the same end thereof. Again, a further object is to avoid the location of any valves in the power plunger. Still another object is to locate the valves in such a way as to obtain a reaction from either the valve mechanism or the delivered high pressure liquid or both of them or from neither of them. Further objects of my invention will appear from the detailed description of the same hereinafter.

While my invention is capable of being carried out in many different ways I have shown only certain forms of my invention in the accompanying drawings in which Fig. l is a diagrammatic representation of an automotive vehicle equipped with my invention;

Fig. 2 is a longitudinal section of a power unit made in accordance with my invention;

Fig. 3 is a transverse vertical section of the power unit shown in Fig. 1, taken on line 3--3 of Fig. 2; v

, Fig. ,4 is a longitudinal section of a modified form of said power unit, shown diagrammatically;

Fig. 5 is a diagrammatic longitudinal section of a power unit deriving its reaction only through the valve mechanism;

Fig. 6 is a similar view of a power unit deriving its reaction only from the delivered hydraulic liquid; and

Fig. 7 is a similar view of a power unit which is non-reactive.

In the drawings, referring first to [Figs 1 to 3, I have shown an automotive vehicle having front wheel brake cylinders l and 2 and rear wheel brake cylinders 3 and 4 provided with hydraulic branch pipes 5 which are connected together by a hydraulic pipe system 6 having a pipe 1 to receive the hydraulic fluid of any desired character for operating the brake cylinders. On the automobile, there is the usual pedal 8 located on a pedal lever 9 carried by a pivot ID on the automobile chassis, the same being provided with a retracting spring I I connected to the chassis. Below the pivot 10 there is a pivotal connection I2 carrying a link l3 which is pivotally connected to the usual master cylinder piston rod 14 passing into a master cylinder l5 having at the upper portion thereof a vested filling cap 16 leading to a reservoir ll forming, a part of the master cylinder l5. Said master cylinder has the usual boot I3 around the piston rod [4, carrying a piston l9 in a cylinder 20 for delivering the hydraulic liquid from the master cylinder by a pipe 21 to an inlet opening 22 in a screw fitting 213, in the power unit. The screw fitting 23 is provided with an apertured baffle 24 and is screw-threaded into a tubular portion 25 of an end casting 26 which is secured in any desired way to a valve casing 21. The valve casing 21 is secured to an apertured spider 28 by screws 23. Adjacent to the valve casing 21 there is a ring 30 to which there is secured an outer shell 3| having clamping bands 32 and 33 to secure the outer shell 3|, in any desired way, at any place on the chassis of the automobile. The other end of the shell 3| has secured thereto a cap 35 located over the end of a hydraulic cylinder 36, where it is secured in place by a nut 3'1. Within the end of the cylinder 36 there is screw-threaded a fitting 38 which is connected to the pipe I,

The manually supplied liquid, received in the inlet opening 22 in the fitting 23, passes into a cylinder 39 in which there is located a plunger 40 having a U-shaped rubber seal 4|. The said plunger 40, furthermore, has a series of radial holes 42 leading to a chamber 43 in the plunger 40 formed by a valve plunger 44 having a reduced end 45, to which there is attached a valve member 46 by a screw 4'! to the end of the valve end of the chamber 39 there is a port 50 which leads to a fitting 5| and a pipe 52 which has another fitting 53 screw-threaded in the valve casing 21' and at this point the valve casingj ZI-fis secured, in any suitable way, to a pipe 54lwhi ch 3 extends inside of the shell 3! to a screw fitting 55 in the side of the cylinder 36 so as to deliver initially the liquid under manual pressure to the brake cylinders 5. Furthermore, the right hand end of the valve plunger id has a screw-thread 56 for securing thereto a valve operating plunger 51 carrying a U-shaped rubber seal 58. This valve operating plunger 57, furthermore, has a reduced extension on which there is securely fastened a vacuum controlling admission valve 60 which is normally moved into open position by a small helical spring 6i which seats on a shoulder 62 on the plunger 5] at one end and which, at the other end thereof, is located around a boss ti on the spider 28. It should also be noted that the casting 26 has a lateral port 64 communicating with an opening 65 which is normally closed by a screw plug W but which may, if desired, communicate with the brake system of a trailer. The vacuum which is controlled by the valve-fit, is communicated thereto by a passageway 67 in the valve casing 21 and which has therein a check valve 88 cooperating with a valve seat 69. The said check valve 68 has a series of peripheral notches it for the passage of the pressure fluid. The vacuum is supplied to the passageway til from a screw fitting H which communicates by a pipe is with a manifold "F3 on the engine of the automobile. Furthermore, the said vacuum passageway 5'6 communicates with a passageway i l for supplying vacuum to the inside or the shell SI. Between the casting 26 and the valve casing 2? there is an air chamber I5 which may be filled with horsehair, and the said chamberis enclosed by a cover plate 76 which is secured on the outside of the casting 25 by a nut 77 and which rests near its periphery upon a series of fingers it formed on the periphery or the valve casing 21. A peripheral gap '59 remains open around the edge of the cover plate It for the entry of air. The vacuum valve fill, when closed, is arranged to seat on a diaphragm "Ell which is clamped against the valve casing 2'! by a clamping ring Eli which rests against the face 'of a second diaphra'gm'dfi secured between i the valve casing 27 and the spider 23. Mounted on the two diaphragms Eli and 82 there are a clamping ring '83 and a spacing ring t4 having peripheral radial apertures 85, the same being secured together with an air inlet valve 88 and the two diaphragms Bil and $32 as well as a retain'in'g ring 8?, by means of rivets it. A large 'h'elical spring 89, supported on the spider 28 at one end and on the ring 33 at the other end,

normally moves the air inlet valve 86 outwardly, P

whereas at "other times its periphery rests against the diaphragm 8t). Also, there is a central open- "90 in the ring 83 to conduct the vacuum, when the valve in is open, through the spider 2f8'to a chamber 9! within a power cylinder 92, which is supported at one end thereof by the ring 30. The other end or" the cylinder 92 is welded, :or otherwise fastened, to a cylinder head 93, having apertures 93a, which is carried in a peripheral recess 9 t on the cylinder 36. The said cylinde'r 33 has a power intensifying chamber 95' in which there is arranged to reciprocate a plunger '98 carrying a U-shaped rubber seal 9'7, and the plunger 96 is guided within the cylinder 95 by a bushing 98 carried within and secured to a sleeve 99 "screw -threaded to the interior of the cylin- "der' The said plunger '96, at the other end thereof, is fastened to a piston head "I00 by "means of a screw ml, and the said piston teed-1 I0!) is normally moved to the left by means of a helical spring I02 which at the other end rests against the cylinder head 93. The piston head I00 is arranged to fit tightly in the cylinder 92 by means of a leather washer I03 which is retained around the periphery thereof by means of a spring plate or disk IEM carried on the screw Illi. Also carried on the screw IilI there is a dished retainer plate I65 which supports around its periphery a felt ring I06. As shown in Fig. 2, the air which enters the chamber I5 passes therefrom through a screen Ital, Fig. 3, located near the periphery of the valve casing 21 so that the airthereirom can reach an annular chamber IE8 which communicates by air passages I69 with the outer face of the air inlet valve 86, so that the said air, when admitted, beneath the periphery of the valve 88, can pass by the passages 35 through the spider 28 and thence to the chamber 9| so as to act upon the face of the piston head I00.

In the modification of my invention in Fig. 4, there is shown diagrammatically a modified form of the power unit for operating the wheel brakes of an automotive vehicle. As shown therein, I have provided a pedal Iitl carried by a pedal lever III mounted on a pivot 'I I2 carried by the chassis of an automobile. The lever III has a pivot II3 for a link I M which is connected to a piston rod IIE having a piston H6 operating in a master cylinder Ill. The master cylinder has the usual reservoir H8 provided with a vented filling cap H9 and a liquid compensation port I20 to supply liquid to a cylinder ill in the retracted position of the piston lit. The cylinder IIl is connected by a pipe I2I to an inlet opening I22 in a Valve casing I23 which is provided with a chamber IN which connects with a passageway I25 in a monitor piston I26 screwthreaded into the side of the valve casing I23. The passageway I25 communicates with a chamber I-2l in the end of a hollow plunger I28 having a piston [28a which is provided with a leather sealing ring 829 fitting within a power cylinder I30. The plunger I23 has an internal annular seal I3tla. The plunger I28, also, has a rubber seal I-3I carried by the cylinder I32. Beyond the right hand end of the plunger I28 there is a hydraulic pressure increasing cylinder I32 form'- ing a part of the cylinder Hi], the cylinder I32 being connected by a pipe I33 to branch pipes I34 and I35 leading to brake cylinders I36 and I3? respectively, which are connected, respectively, to brake shoes I38 and I39 on the rear wheels of the automobile. It will be understood, of course, that similar branch pipes and brake cylinders may be connected to the pipe I33 leading to front wheel brakes on the automobile, if desired.

Within the chamber EEK-in the fitting I22 there is also provided a valve stop I149 adjacent to apertures 441.. The said stop I 50 cooperates with a web I42 which is attached to avalve M3 in the upper or retracted position of a plunger I44. The valve M3 is located in a recess. I45, having a helical spring I46 to normally seat .the valve 'I ttagainst a valve seat I 11, in plunger head I 58 "screw threaded to the plunger EM.

The plunger head I48, furthermore, has a rubber seal M9 operating within a chamber I50 in the valve casing I23. Communicating with the chamber I50 there are a plurality of radial ports I.5I leading to the recess :45. Furthermore, the said chamber I50 has a lateral .por t 1952-1Whi0h communicates with aipipe 'I 53 leading to a. port 454111. the pressure increasing cylinder "I32. A't

its lower end the plunger I44 passes through a seal I55 in the valve casing I23 and contacts with a valve stem I56 on whichthere is carried a vacuum valve I51 adapted-to seat on a valve seat I58 carried by a screw ring I59 having a .series of internal flutings I60 for guiding the valve stem I56. The valve .ring I59, furthermore, is screw-threaded to an air inlet valve member I6I normally pressed upwardly by a helical springI62 seated within a spacing ring I63a secured by screws I63b to the valve casing I23 and to a cap I63 by screws I64. Between the spacing ring I'63a and the valve casing I23there is clamped, at its outer periphery, a diaphragm I65, the inner periphery thereof being clamped between the screw ring I59 and the air inlet valve member I6I. It will be noted, furthermore, that the air inlet valve member I6I has a flange valve I66 which cooperates with a valve seat I61 on the spacing ring I63a and that the said valve member IOI has a series of longitudinal passageways I68 to act to permit the passage of air On the stem I56 there is a shoulder I69 supporting a helical spring I10, the lower end of which is supported by an adjusting screw I1I screwthreaded in the cap I63. The cap I63, furthermore, is connected by a pipe I12 to an inlet I13 leading to a chamber I14 in the power cylinder I30. Also, within the spacing ring I63a there is a chamber I having an air inlet pipe I16 covered by a cap I11 supported therefrom by a spider ring" I18 having air inlet apertures I19. The valve casing I23 has a vacuum chamber I89 which communicates by a port I!!! with a pipe I82 which is connected to the manifold of the automobile engine. Also, said valve casing has a vacuum pipe connection I83 leading from a port I84 in the valve casing I23 to a port I35 in a vacuum chamber I86, at the right of the piston I28a, in which there is located a helical spring I81 supported at one end by the cylinder I30 and at the other end against a ring I88 which is pressed by the spring I81 against the leather washer I29 to retain it in place.

In Figs. 5, 6 and '7 I have shown, diagrammat ically, other modifications of my invention, each of which, preferably, has a liquid compensator and hydraulic cut-01f valve located at the inlet end of the apparatus. These modifications of my invention illustrate the manner in which the reaction on the manual means, during the operation of the apparatus, may be effectively controlled so as to obtain the reaction only from the modulator valves, asin Fig. 5, or to obtain a reaction only from the hydraulic pressure liquid applied in operating the brakes, as in Fig. 6, or so as to avoid any reaction from the valve mechanism and the hydraulic pressure liquid applied to the brakes, as in Fig. '7.

In the form of my invention as shown in Fig. 5, I have provided the usual pedal I89 mounted on a fixed pivot I90 having a pivotal connection I9I by a link I92 to a piston rod I93 in a master cylinder I94 which i connected by a hydraulic line I95 to an inlet I96 on a combined plunger and diaphragm housing I91. The housing I91 has a flange I98 enclosed by a U-shaped split ring I99, the ends of which have a bolt 200 pulling them together in a peripheral direction. Said ing I99, also, clamps a flange I of a diaphragm 206 to Wheel cylinders 201 of front-"and rear wheels 208 on the automobile. The cylinder 204 receives one end of a rearwardly directed plunger 209 which is clamped to the middle portion of .a flexible diaphragm 2I0 by a clamping plate 2 and screws H2. The outer periphery of the diaphragm 2I0 is clamped between the flanges I98 and 20 I; by the clamping ring I 99. Integral with the plunger 209 and at the forward end thereof, there is a smaller plunger 2 l3 which slides within a sleeve 2I4 carried by the cylinder I91. The forward end of the sleeve 2I4 has an aperture 2I5 which is connected by means of a chamber 2I6 to the hydraulic inlet port I96. The aperture 2I5, furthermore, provides an opening through which a Valve stop rod 2I1 can contact with an end 2H3 of the cylinder I91 so as to unseat a liquid compensation and cut-off valve 2 I9 which is pressed against its seat 220 in a passageway 22I extending through the plungers 209 and 2I3.

The valve 2I9 thus becomes unseated in the retracted position of the piungers 209 and 2 I3 when the manual pressure is removed from the pedal I89. At other times the valve 2I9 is pressed against its seat by a spring 222. The sleeve 2I4 serves as a movable operating means for a projection 225 on a valve operating lever 226 which has a pivotal support 221 by means of ears 228 on the plunger 209 at one side of the plunger 213. At one end, the lever 226 has a spring support 229 from the plunger 209 and near its other end carries an adjustable screw-threaded stop 230. At this end of the lever 226 there is a pivotal connection 23I to a valve operating rod 232 connected to a vacuum inlet valve 233 cooperating with a valve seat 234 on a subsidiary diaphragm 235 which is connected to an air inlet valve sleeve 236 having an air inlet valve 231 for cooperating with an air valve seat 238. A spring 239 is provided for normally seating the air valve 231 on its seat 238. It will be understood that this vacuum and air valve construction is the same as shown in detail in Fig. 4 described here inabove. The said spring 239 is located in an air chamber 240 which leads to a passageway 24I in the plunger 209 passingaround the passageway 22I and which ends in a nipple 242 connected by a flexible conduit 243 to an air inlet port 244. This form of power unit, in Fig. 5, provides areaction only from the modulating valve construction, and as the valve 2I9 is mounted on the plunger 209'110 reaction is transmitted from the delivered high pressure liquid from the conduit 265 to the conduit I leading to the master cylinder.

The modification shown in Fig. 6 is constructed the same as the modification shown in Fig. 5, except that in this instance a piston 245 is shown fitting within a cylinder 246 and except for the arrangement of the valves. In this instance, I have provided on the cylinder 246 a smaller cylinder 241 having a plunger 248 within the same,

which is provided with a cylindrical aperture 249 through which there extends a valve operating rod 25I with intermediate liquid transmitting passages 252. The rod 25I is carried by a valve 253 which is pressed against a valve seat 254 on the interior of the sleeve 248 by means of a spring 255 seated at its forward end against a plunger 256, having a longitudinal passageway 251. The plunger 256 slides within the sleeve 248: and is arranged to rest against the rear end of a valve operating lever 258 having a central aperture 259 to permit the plunger 256 to pass through the same. The upper end of the valve operating lever 258 has a pivot 260 connecting it to a valve operpistoniz i 5.

7 'ating rod .261 on a valve 262 which :seats against a valve seat 253 within the piston 245 which is connected by a passageway rt l to the chamber within the cylinder 24-6 at the'le'ft'of thepiston M 5. A spring 1265, supported on a seat 256, normallypresses the valve 232 to the right so as to open ports 26? leading from the chamber 263 to the right 'face of the piston M5. Thesaid'valve 262, thus, normally conveys the vacuum from the left to' the right face of the "piston 245. The

*lower end of the .valve operating lever 258 has a "pivot :ZBSoonnecting it tea valve operating red sea on an air inlet valve 'Z'l-ii which :is normally pressed against avalve seat 21.! by :a spring 1272 carried by a recess 2'53 in a chamber 274 in the The saidchamber 2 74 has a port 215 connecting it to the right face of the piston 24.5 and has a passage E l'li leading to a :nipple 211 connected by a rubber tube rm to :a vent, as shown in the modification shown in Fig. .5. This .mo'dification of my invention .shown in Fig. *6,

thus, receives on the :manual means thehydraulie reaction from the hydraulic liquid applied by the power unit to the Wheel-cylinders, but on account of the manner in which the valves are mounted the manual zneans does not receive any substantial reaction from the modulating valve -operating mechanism.

Inithe form of my inventionsh-own in Fig. 7,'I :have provided a construction the same a that "shown inul lig 5,except that in this instance I have utilized a piston 21% instead of the diaiphragmi2 idandexcep't that I have arranged the 'rnodulating valves differently, a liquidcompensation 'and :cu't-off valve 280 being provided, the *same as that shown in. Fig. 5. tin Eigqfl, there shown an emergency brakeop- In this instance,

crating lever 2? instead of the pedal i89iof Fig.

'5. Also in this instance, instead of the modulatingvalve construction shown in Fig. 5, I have ishown a vacuumadmission valve 282 and a valve seat 283 therefor, which are the same as the vacuum admission valve 252, 263 ofFig. 6, and an air :inlet valve 284 with a cooperating valve sea-V285, which are the same as the valve 210, 21-1 :of Fig.6. Also, in this instance, Ihave provided a modulating valve operating lever 286 which is the same as the valve operating lever construction 258 in Fig. 6. In this form of my invention, owing to the mounting of the'cut-ofl valvetBll on the piston 219 and the manner-of -mounting-and seatingthe valves 232, i233 and 284, 285-011 the piston 2 9, no reaction is receivedon the manual means from the hydraulic liquidapplied to the wheel cylinders nor from thezvalve mechanism controlling the inlet and outlet-of the vacuum for applying the pressure to the liquid delivered to the Wheel cylinders. Therefore, in this construction the apparatus is substantiallya non-reactive travel controlmechanismfor apply- :ing hydraulic pressures from a :power unit in the operation of the brakes or otherparts-to be moved ithere by.

. Inithe operation of the fornrof my invention uShOWIi in Figs. 1, 2and 3, assuming that themotor f the automobile :is in operation and that a vacuum is accordingly supplied "to the pipe t2, when manual pressure is applied to the ;pedal"8, :this operates the piston 2i 9 inthe'mastcr cylinder 15 so as to apply hydraulic fluid under pressure through :the pipe 2! to 'theiinlet 22 .011 the power units. This will .at first supply the pressure fluid around valve, 128,, to into the chamber c3 :and thence through :theports #2 to .the chamber .39 and from this chamber through the pipe 1 tothe zbrake cylinders ,so was t01be applied to .the.-;brake cylinders 1, :2, .3 and A on the four wheels .of the automobile. It Willfibe understood that some braking force can be ap- .plied manually linxzthis way,:if desired, particularlyaof the power mechanismfor any reason fails to operate, asnfor instance when a failure 40f "vacuum should occur., .Asxthe manual pres- :sure is increased, however, this :results inmos- ,:ing the valve 48., 4.9 on :thesleevedfi, thereby cuttin on the communication of the liquid 7 from the :inlet 12 :toxthe {chamber .39 and emovingthe sleeve to and plunger J51 rearwardly so as to :rolose the vacuum-admission valve fiiland thereafter unseat the .air inlet valve 86 which admits airrthroughrthe air inlet It! from around "also, that the amount of pressure applied liquid ,passes through the recesses 114! through the pipe :1, Whether :manually or ,by

,means of power or both, to the brake cylinders 15 -will be :felt on the pedal 8 by the operator thereof by reason of thewpipe connections 52,

'54 -.operating in connection \with the difierential ,plungers .40 and 51,."1311115 obtaining, also, a

definite ratio of input tooutput force. .In other words, the :brakes can, thus, be controlled manually so .as torappl-y the :manual pressure or .pressure..derived .iromathe power means in mod- .ulated amounts, according to the on or. =0ffmodulation of the valves 5d, .85, "which i are arranged to be self-flapping so that both of said valves .are in closed position before any change inthe direction of movement thereof, to admit more air through the ,airdnlet iii'i past the air .inlet valveBE, or to apply more vacuum past ;:the valve-.60. ,It 'will .be noted, furthermore,

that in the apparatus the cut-off valve it, .419

as :weu as the modulating valves :63, 386 are .lo- .cated at .the ,samc,end ofthe structure, so that the construction is accordingly ,greatly simplilied and the connections thereto .can .be more readily made when installing the unit on the chassis ofthe automobile.

Imthe modification of my invention shown in .Eig. l ithe operation .is somewhat similar and there :is a further .fsimplification in mounting the nut-,ofi valve J 43 and .the modulating valves lfiliand .lfil altogether on vone end of the power unit. In this instance, when manual pressure .is .applied ,to the pedal .l jlfluthe master cylinder H] supplies the fluid .under pressure through ,thepipe .l2.l to the inlet J22 where initially the adljacent ,to the stopl lfi which, in the initial re- .tractedpposition of the plunger i4, l,,retains the :valve 1.43 .open zbyireason of .the web m2. liquidithuspunder, manual pressure, passes into the -=chamber M5 through the radial ports 15.1 andthence into the chamber .150 .and'by the 13193153 the ,cylinder l32andthencethrough thepipe-JSS to thelbrakecylinders 'l36.and 13 i,

thus-settingthe :brakes. v,IIpon the increase of the manual pressure .theplunger 1.44 ismoved .forwardly, .thus closing the valve I43 ,and'thereafteri-moving the vacuum outlet valve 15! ,into

closed position followed by the opening of the air inlet valve I66 which admits air from the pipe I16 past the valve I66 into the pipe I12 and thence into the chamber I'M in the power cylinder I30. The piston I23, having been previously submerged in a vacuum, is now moved to the right by the air pressure in the chamber I14, thus moving the end of the said piston into the cylinder I32 and producing an intensi" fied pressure which is supplied by the pipe I33 to the brake cylinders I36, I31. This application of the intensified pressure is, thus, controlled in modulating amounts by the operation of the valves I 51 and IEiI, which are selflapping so that they are both closed in changing from a position in which both valves are closed to a position where more air is admitted to apply greater braking force, or to a position where more vacuum is admitted to apply a less ened braking force. Throughout the applica tion of manual force or intensified pressure from the cylinder I32, there will be a coordinate feel sensed by the operator on the pedal Hi3, ac cording to the amount of braking force applied. Also, in this form of my invention there is provided a coordination of the travel of the pedal with the amount of travel of the brake operating elements by reason of the monitor chamber I21, for the reason that as the piston I28 moves towards the right a coordinate amount of fluid is drawn into the chamber II. so that the operator of the pedal II I] not only has feel but also senses the change of position which is coordinate to the amount of braking pressure and intensified pressure liquid supplied. to the brakes. In this construction it will be noted that all the valves are conveniently located on one end closure for the power cylinder. Also, in this instance, the reaction is felt on the manual means from both the modulating valves and the hydraulic power pressure exerted on the brakes.

In the operation of the power unit shown in Fig. 5, and in which it will be noted that the liquid compensation and cut-off valve ZIQ is located at the inlet end from the power unit, when the manual pressure liquid delivered by the master cylinder I94 is received in the inlet 1%, this liquid, under manual pressure, passes iiirectly through the passageway HI and the pipe 2E6 to the brake cylinders 2M, owing to the I fact that the valve M9, 221: is unseated by the stop rod ZI'I contacting with the end 2H3 of the cylinder I91. The wheel brakes will, thus, be given their initial movement in this manner, as for example to set the brakes and perhaps apply some of the braking pressure. When the manual pressure in the pipe I95 is increased,

however, the plunger 289 will be moved for'-' wardly, thus moving the stop rod 2I'I out of contact with the end ZIB of the cylinder I9! and seating the valve 2| 9, 220. This forward movement of the plunger 209 is brought about by the movement of the sleeve 21d forwardly by the manual pressure, thus moving the valve lever 226 to seat the vacuum valve 233, 234 followed by the unseating of the air inlet valve 231, 238 which admits air from the air port RM to the right face of the diaphragm ZIQ, result ing in the movement of the plunger M9 to wards the left. In any position or" rest of the foot thus attained on the pedal I89 the air valve 231. 238 will become seated in lapped position with regard to the valve 233, see. Further forward movement, due to increased manual pressure, will again unseat the air valve 10 231, 238 to apply further movement of the plunger 209 towards the left so as to exert a higher braking eifort on the braking cy1inders 201. In the release of the pressure from the brakes the air valve 231, 238 will close and the vacuum admission valve 233, 234 will open, thus restoring the vacuum to both sides of the diaphragm 2H1. During this operation of applying hydraulic liquid under power pressure to the wheel cylinders 20'! the reaction on the manual means will be due only to the amount of air pressure exerted on the right face of the diaphragm 2 It by the operation of the modulating valve means and owing to the modulating valve being mounted on the diaphragm 235.

In the operation of the form of my invention shown in Fig. 6, the operation is the same essentially as Fig. 5 with the exception that a different reaction is obtained on the manual means owing to the difference of arrangement and operation of the valves. In this instance it will be noted that the liquid compensation and cutoff valve 253, 25 i is mounted on the valve operating sleeve 248 and that the sleeve 248 operates a simple type of valve mounting which does not.

receive a reaction from the air pressures admitted, to any substantial extent. Accordingly, the

reaction of the manual means in this instance is the reaction from the hydraulic pressure liquid applied by the power from the power unit on the brake cylinders.

In the modification of my invention shown in Fig. 7, the operation is a further modification of the operation of the apparatus shown in Fig. 5 inasmuch as in this instance the reactive modulating valves are not present and, the liquid compensation and cut-off valve 280 being mounted on the piston 219, there is substantially no reaction either from the valves or from the power hydraulic pressure liquid applied to the wheel cylinders, so that as a consequence travel control without a reaction is attained in applying the power from the manual controlling means 28I by means of the power piston 219 to the wheel brake cylinders.

While I have described my invention above in detail I wish it to be understood that many changes may be made therein without departing from the spirit of the same.

I claim:

1. A power unit comprising a movable wall, a: chamber in which it moves, a connection on the power unit adapted to be connected to a source of pressure diifering from the atmosphere, a

venting connection, a valve means, having aplunger connected to the valve means and a chamber for the plunger, for controlling the application of the pressure from said source and from the venting connection to the movable wall, a second plunger connected to one side of the movable wall and having a plunger chamber,

a hydraulic outlet for pressure liquid connected to said plunger chamber, a hydraulic inlet for pressure liquid connected to said first mentioned plunger for control of the valve means and a third plunger connected thereto, said hydraulic inlet and third plunger being located on the other side of the movable wall, and a liquid com 11 third plunger; said first mentioned valve means being" constructed and arranged" to exert a reactiori from the air, admitted by the venting means, onsaid hydraulic inlet.

2. A- power unit comprising a movable wall; a chamber in which it moves, aconnection on the power unit adapted to be connected toa: sourceof pressure difiering from the atmosphere', a venting connection, a; valvemeans mounted on the movable wall, having a plunger connected to the valve'mean's and a chamber for said plunger, for controlling the application of pressures from said source and from the venting connection to the movable Wall; a second plunger connected to one side of the movable wall and having a plunger chamber, a hydraulic outletfor pressure liquid connected to said plunger chamber, a hydraulic inlet for pressure liquid connected to said first mentioned" plunger" forcon'trol oftlie valve means and a thirdplunger connected thereto, said hydraulic inlet and third plunger being located on the other side of the movable wall, and a liquid compensating valve on said other side of" the ll'l'OValblEWvalll; connected for operation with" and movement by the thirdplunger to seat the compensating valve and said liquid" compensating valve being located a passageway connecting the hydraulic inlet to the hydraulic outlet, having a liomid compensating valve seat carried by the thirdplunger, said first mentioned valve means being construeted a ranged to exert a reaction from the air, admitted by the venting means, on sa'id hy draul io inlet,

3'; A power unit comprising amovable wall;v a chaniberin which it moves, a connnection on the'i'power uni-t adapted: to: be connected to:- a source" of pressure" differing from the" atmosphere, a' venting connection',.- a valve means, havifig a plunger connectedito. the" valve means and a chamber for the plunger, for controlling the application of the pressuresfrom said source and from: the venting. connectionto the movable wall, a second plunger connected to one side'- of the movable wall and having a-plunger cham bet, a hydraulic outlet for pressure liquid connected to said plunger chamber, a hydraulic inlet for pressure liquid connected to said: first mentioned plunger for control of the valve means and a third plunger connected thereto, said hydraulic inlet and third plunger being located on the other side of the movable wall, the: third plunger having an operative connection to said valve means, anda liquid compensating valve on said other side of the movable wall, connected for operation with and movement by the third:

plunger to seat the compensating valve said liquid compensating valve being locatedxin a pas-' sage-way connecting the hydraulic inlet to the hydraulic outlet, having a liquid compensating valve seat carried by the third plunger, said first mentioned valve means being constructed and arranged to exert a reaction from the air ad initted by the "venting means, on said hydraulic inlet.

'4. A power 'unit comprising a movable wall, a chamber in which it moves, a connection on the' povver 'uni't adapted. to be connected to. a source or pressure differing from the atmosphere, a venting connection, valve means, having a plunger connected to the valve means and a chamber for the plunger, for controlling the "applicat'ion of the pressures from said source and from the venting connection to the movable wall, a second plunger connected to one side of the 1'2 movable wall and having a plunger chamber, a hydraulic outlet for pressure liquid connected to said plunger chamber; a hydraulic inlet for pressure" liquid connected to: said first mentionedplunger for control of. the valve means and a third plunger connected thereto, said hydraulic inlet'and' third plun'ger'being located on the' other side" of the: movable wall, and a liquid compensating valve on said other side of the movable wall, connectedfor operation with the movement of the third plunger to seat the compensating: valve and said liquid compensating valve being located in a passageway connecting the hydraulic" inlet to the hydraulic outlet, havingra liquid compensatin'g valve seat located in a passage within the thi rd'plunger, said first mentioned. valve means being constructed and arranged to: exert a re action' from the air; admitted by the venting means, on said hydraulic inlet.

5.- A power unit comprising a movable wall, a chamber in which it moves, a connection adapted to be connected to a source of pressure difiering from. the atmosphere, a venting connection, a valvem'eans, a plunger and: a chamber for the plunger; said plunger being connected to said valve means for controlling the application of the pressures. from said sourcev and from the amount of the air admitted iromthe vents ing connection to the movable wall, a second plunger connected'to" one side of the movablewall' and having a plunger chamber, a hydraulic outlet for pressure liquid connected to said: plunger chamber, a hydraulic inlet for pressure liquid connected to said first mentioned plunger for control of the valve means, and a tiurd plunger located in a chamber connected to said inlet, said-hydraulic inlet and last mentioned plunger being located on the other side of the movable wall,;and' a liquid compensating valve on said other side of. the movable wall, connected to the third plunger chamber; and located in a passageway connecting the hydraulic inlet to the hydraulic outlet, having: a valve seat-located. in a passage within the third plunger, said valve means being constructed and arranged to exert a reaction from the difierential pressure due to amount of the air, admitted by the venting means, on the liquid in said hydraulic the said valve means having a lever connected to said first mentioned plunger and provided with valveoperating portions on the opposite sidesof a pivotal connection from said lever to the movable wall.

6. A power unit comprising a movable wall, a chamber in which it moves, a connection adapted to be. connected toa source of pressure differing from the atmosphere, a venting connection, a valve means, a plunger and a chamber for the plunger, said plunger being connected to said valve means for controlling the application of the pressures from said source and from the amount of the air admitted from the venting connection to the movable Wall, a second plunger connected to one side of the movable wall and having a plunger chamber, a hydraulic outlet for pressure liquid connected to said plunger chamber, a hydraulic inlet for pressure liquid connected to said first mentioned plunger for control of the valve means, and a third plunger located in: a chamber connected to said inlet, said hydraulic inlet and last mentioned plunger being located on the other side of the movable wall, and a liquid compensating valve on said other side of the movable wall, connected to the third plunger chamber and located in a pas-- sageway connecting the hydraulic inlet to the hydraulic outlet, having a valve seat located in said passageway within the third plunger, said valve means being constructed and arranged to exert a reaction from the differential pressure due to the amount of the air, admitted by the venting means, on the liquid in said hydraulic inlet, the said valve means having a lever connected to said first mentioned plunger and provided with valve operating portions on the opposite sides of a pivotal connection from said lever to the movable wall, and a spring located on the third plunger for seating the compensating valve.

'7. A power unit comprising a movable wall in the form of a diaphragm, a connection adapted to be connected to a source of pressure differing from the atmosphere, a venting connection, a valve means, a plunger and a chamber for the plunger, said plunger being connected to said valve means mounted on a subsidiary diaphragm on the first mentioned diaphragm for controlling the application of the pressures from said source and from the amount of the air admitted from the venting connection to the movable wall, a second plunger connected to one side of the movable wall and having a plunger chamber, a hydraulic outlet for pressure liquid connected to said plunger chamber, a hydraulic inlet for pressure liquid connected to said first mentioned plunger for control of the valve means, and a third plunger connected to said inlet, said hydraulic inlet and last mentioned plunger being located on the other side of the movable wall, and a liquid compensating valve on said other side of the movable wall, connected to the third plunger and located in a passageway connecting the hydraulic inlet to the hydraulic outlet, having a valve seat associated with the third plunger, said valve means being constructed and arranged to exert a reaction from the differential pressure due to the amount of the air, admitted by the venting means, on the liquid in said hydraulic inlet.

8. A power unit comprising a movable wall, a chamber in which it moves, a connection on the power unit adapted to be connected to a source of pressure difiering from the atmosphere, a venting connection, a valve means, having a plunger connected to the valve means and a chamber for the plunger, for controlling the application of the pressures from said source and from the venting connection to the movable wall, a second plunger connected to one side of the movable wall and having a plunger chamber, a hydraulic outlet for pressure liquid connected to said plunger chamber, a hydraulic inlet for pressure liquid connected to said first mentioned plunger for control of the valve means and a third plunger connected thereto, said hydraulic inlet and third plunger being located on the other side of the movable wall, and a liquid compensating valve on the said other side of the movable wall, connected for operation with the movement by the third plunger to seat the compensating valve and said liquid compensating valve being located in a passageway leading from the other side of the movable wall, connecting the hydraulic inlet to the hydraulic outlet, having a liquid compensating valve seat carried by the third plunger, said first mentioned valve means being constructed and arranged to exert a reaction from the air, admitted by the venting means, on said hydraulic inlet.

9. A power unit comprising a movable wall, a chamber in which it moves, a connection adapted to be connected to a source of pressure differing from the atmosphere, a venting connection, a valve means, a plunger and a chamber for the plunger, said plunger being connected to said valve means for controlling the application of the pressures from said source and from the venting connection to the movable wall, a second plunger connected to one side of the movable wall and having a plunger chamber, a hydraulic outlet for pressure liquid connected to said plunger chamber, a hydraulic inlet for pressure liquid connected to said first mentioned plunger for control of the valve means, and a third plunger connected to said movable wall, said hydraulic inlet and last mentioned plunger being located on the other side of the movable wall, and a liquid compensating valve on said other side of the movable wall, connected for operation with and movement by the third plunger to seat the compensating valve and located in a passageway leading through both said second and third plungers connecting the hydraulic inlet to the hydraulic outlet, having a valve seat associated with the third plunger, said valve means being constructed and arranged to exert a reaction from the air, admitted by the venting means, on said hydraulic inlet.

EDWARD A. ROCKWELL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,260,491 Stelzer Oct. 28, 1941 2,275,697 Stelzer Mar. 10, 1942 2,300,136 Rockwell Oct. 27, 194 2,353,755 Price July 18, 1944 2,359,687 Stelzer Oct. 3, 1944 2,374,545 Ingres Apr. 24,1945 2,377,699 Klimkiewicz June 5, 1945 2,398,252 Rockwell Apr. 9, 1946 2,433,953 Ingres Jan. 6, 1948 OTHER REFERENCES Commercial Car Journal, issue of Sept, 1943, page 64. 

